DESCRIPTION: The investigators propose to test the feasibility of using their purified bovine hemoglobin-based product as a contrast agent for blood oxygenation by magnetic resonance imaging, as further described by their abstract: "This proposal will test the hypothesis that Biopure's clinical formulation of hemoglobin (HBOC-201) is a natural 'functional' contrast agent for magnetic resonance imaging (MRI) and will enhance blood oxygen level dependent (BOLD) imaging contrast. BOLD imaging makes use of the increase magnetic susceptibility of deoxygenated hemoglobin (deoxyHb) compared to oxygenated Hb (oxyHb). Specifically the transverse relaxation rates R2* of mobile protons is increased when in proximity of deoxyHb. HBOC-201 is hypothesized to increase the sensitivity of MRI to detect changes in deoxyHb and thereby provide information on tissue oxygenation. We will determine the extent of HBOC-201 induced increases in sensitivity to controlled changes in arterial oxygen tension using multi-echo quantification of the relaxation rates, R2*. The hypothesis will be tested using two in vivo models, the hypoxic rat brain, and hyperoxic rat astrocytoma. The combination of MRI and HBOC-201 contrast agent holds the exciting promise of being able to selectively monitor tissue oxygenation and thus revolutionize realtime evaluation of tissue oxygenation in disease, trauma, and during medical procedures. This technique will be of particular value in brain mapping, evaluation of disease states where there is dysfunction with perfusion and/or oxygenation, and planning surgical procedures." PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE